Elasticsearch uses a hybrid mmapfs / niofs directory by
default to store its indices. The default operating system limits on mmap
counts is likely to be too low, which may result in out of memory exceptions.

On Linux, you can increase the limits by running the following command as
root:

sysctl -w vm.max_map_count=262144

To set this value permanently, update the vm.max_map_count setting in
/etc/sysctl.conf. To verify after rebooting, run sysctl vm.max_map_count.

The RPM and Debian packages will configure this setting automatically. No
further configuration is required.